Abstract

• The purpose of this study was to prepare low alcoholic fruit beverages through fermentation of grape juice and apple juice with kefir grains and optimum conditions for fermentation has been studied. The present study includes phytochemical investigation of selected fruits (grape and apple), antimicrobial activity and some physicochemical analysis of kefir fermented milk and fruits juice such as pH, titratable acidity, alcohol content, reducing sugar content and total soluble solids were determined. During the12 - 48 h of incubation, pH values of the fermented milk kefir and fruits-based beverages ranged from 5.8 to 3.0. These pH values were similar to those previously reported for kefir beverage. The antimicrobial activity of water kefir, apple juice kefir, grape juice kefir and milk kefir was screened with microorganisms such as three Gram positive bacteria - Bacillus subtilis, Bacillus pumilus, Staphylococcus aureus, two Gram negative bacteria - Escherichia coli, Pseudomonas aeruginosa and a fungus Candida albicans by agar well diffusion method. Milk kefir exhibited higher antimicrobial potency against the test organisms with inhibition zone diameters ranged between 20mm - 25 mm. Apple juice kefir and grape juice kefir also exhibited antimicrobial potency against the test organisms with inhibition zone diameters ranged between 18 mm - 23 mm.